DRUG REACTIONS AND DRUG ALLERGIES

Many of us have had trouble with one drug or another. Some drugs can cause an upset stomach or drowsiness. Some drugs can threaten our lives. Drugs put more than 2 million people into the hospital every year. Drugs cause more than 100,000 deaths every year. The number of serious drug reactions goes up every year.

• Find an allergist to help manage your drug allergy

• Learn more about the different types of drug reactions

A drug reaction is a problem caused by a drug that you or your doctor did not expect. Any prescription or non-prescription drug can cause a problem. Reactions can occur between medications. Most drugs cause trouble by working on your body chemistry.

Rarely, your immune system may react to a drug or to a chemical that your body created from that drug. This type of reaction is called a hypersensitivity reaction. Allergic drug reactions are one type of hypersensitivity reaction.

DRUG ALLERGY SYMPTOMS:

Allergic drug reactions may cause:

• Skin rash or hives

• Itchy skin

• Wheezing or other breathing problems

• Swelling of body parts

• Anaphylaxis, a life-threatening allergic reaction

Reactions can occur in any part of your body.

A “pseudoallergic” or “anaphylactoid” drug reaction looks like an allergic drug reaction, but it is not allergic. This type of reaction can happen when you take a drug for the first time. We see this occur with aspirin or X-ray dye.

DRUG ALLERGY TREATMENT:

For a mild reaction, you may only have to stop the drug.

For a more serious allergic drug reaction that is not life-threatening, your allergist may give you:

• An antihistamine (to counteract the histamine released into your body during the reaction)

• A non-steroidal anti-inflammatory drug or a corticosteroid (to reduce inflammation)

WHAT CAUSES A DRUG ALLERGY?

Any person can get an allergic drug reaction to any drug. Allergic drug reactions are less common than other types of drug reactions.
For a drug allergy to happen, you must have taken the drug before. You might have a reaction that looks like a drug allergy, but is not a true drug allergy. You can outgrow a drug allergy.
If you never had the drug before, then you cannot develop a drug allergy to that drug. However, you might have unknowingly been exposed to that drug in the past.
Penicillin causes most allergic drug reactions. Even If you react to penicillin, you may not react to related drugs such as cephalosporins. 
Sulfonamide containing antibiotics may cause allergic drug reactions. There are many non-antibiotic sulfonamide containing drugs. Most people with a sulfonamide antibiotic drug allergy do not have problems with the non-antibiotic sulfonamide drugs.
You are more likely to have a medication allergy if you get the drug through your veins since the drug goes immediately into your blood system. The higher the amount of the drug in your blood system, the more likely you will have an allergic drug reaction to it. Less often, you can get a drug allergy from swallowing the drug. The more often you take a drug, the more likely you will have a drug allergy to it.

DIAGNOSING DRUG ALLERGIES

Drug reactions can be hard to diagnose. They can look like other diseases. Many of the drug reactions are known. Others may not have been identified yet.

It is important to figure out if the reaction you suffered is allergic or not allergic. Your doctor may ask you to see an allergist.

When you visit an allergist, you can help if you have the following information:

• When did you start and stop the drug

• When did the symptoms begin

• What symptoms did you experience

• How long did your symptoms last

• What other prescription and non-prescription drugs were you taking at the time

• Are you using any herbs, vitamins or health supplements

• What treatments did you receive for the symptoms

You should bring with you:

• Your usual medicines

• Your other drug reactions

• Your medical and surgical problems

• Problems that run in your family

Bring the exact name for all of your drugs. If you can, bring the suspected drug with you. This will help the allergist recommend different drugs, if you need them.

The allergist will give you a physical examination. The allergist will look for problems that are part of the drug reaction. The allergist will look for non-allergic reasons for the reaction.

Skin tests are available for some drugs. Drug challenge tests can be helpful. For a drug challenge, you take the drug and you doctor observes your reaction. If you had a serious reaction, a drug challenge may be too dangerous.

OTHER MEDICATIONS:

Sometimes you can replace the drug with other medicines. If not, then the allergist may offer you a drug desensitization.
Desensitization means taking the drug in increasing amounts until you can tolerate the needed dose. This must be done in a doctor’s office or hospital to get the care you need if you have problems. Desensitization creates only a temporary tolerance to the drug. It helps only when you take a drug consistently. Once you stop the drug, you may need another desensitization if it is needed again.

WHAT IS ANAPHYLAXIS?

Anaphylaxis is a severe, life-threatening allergic reaction. This serious reaction happens within seconds to minutes after you take the drug. With this type of reaction, you may experience:

• Swelling of your body parts, with or without hives

• Light headedness or dizziness

• Sudden drop in your blood pressure, with or without loss of consciousness

• Shock, with damage to your internal organs

Anaphylaxis requires emergency treatment to prevent death and damage to your internal organs. Treatment includes:

• Drugs (adrenaline, antihistamine)

• Intravenous fluid

• Oxygen

These treatments help support your blood pressure and your internal organs. Your doctor may give you a form of steroids. If you stop breathing, the doctor may give you artificial breathing.

If you take a drug and find yourself in the middle of this type of reaction, you and those around you must act fast. Immediately call your local emergency telephone number. Antihistamines might help. Alone, they will not keep you out of serious trouble.

If you carry self-administered epinephrine (adrenaline), then you should take it immediately. If you do carry adrenaline, be sure you really know how and when to use it in an emergency. If you observe someone go into anaphylaxis, then be sure to put the person on their back and raise that person’s feet. Call your local emergency telephone number immediately!

IF YOU HAVE A DRUG ALLERGY:

• Make sure all of your doctors know the drug you took and the drug reactions you suffered

• Check with your doctor about related drugs that you must avoid

• Check with your doctor about drugs that you can take, if needed

• Wear an emergency medical alert bracelet or necklace, with the offending drug engraved

Credit: American College of Allergy, Asthma & Immunology